🚀 go-pugleaf

Damon_Harper@mindlink.bc.ca (Damon Harper) writes:

> A request:
> d
> Could someone please post or send me a simple line-drawing algorithm, in C or
> non-language-specific, it doesn't matter, the method is all I want.  Thanks.
> 
>  ---    ---
> damon harper            Damon_Harper@mindlink.bc.ca
>  ---    ---

The following routine is in Pascal (pseudo-code) and follows Bresenham's
algorithm from the book "Computer Graphics" by Donald Hearn and M. Pauline
Baker:

procedure bres_line(x1,y1,x2,y2:integer);
var
  dx,dy,x,y,x_end,p,const1,const2:integer;
begin
  dx := abs (x1-x2);  dy:=abs(y1-y2);
  p := 2*dy-dx;
  const1 := 2* dy;  const2 := 2* (dy-dx);

  if x1>x2 then begin
    x := x2;  y:=y2;  x_end:=x1;
  end
  else begin
    x:=x1;  y:=y1;  x_end:=x2;
  end
  set_pixel(x,y);   (* you supply this one, just set a pixel *)
  while x<x_end do begin
    x:=x+1;
    if p<0 then p:=p+const1;
  else begin
      y:=y+1;
      p:=p+const2;
    end;
    set_pixel(x,y);
  end
end;

Hope it helps.  Sorry if some C syntax creeped in...

J.L.Fincher, Warlok